Simulated fiber optic VHF channel indicia display

ABSTRACT

A VHF channel indicia display device includes a display window made up of a plurality of discrete light transmissive points arranged in a predetermined format on an opaque field. Means are provided for illuminating the display window from the rear. Movable mask means, driven by the channel selector shaft, are interposed between the display window and the illuminating means. The mask means is opaque and has a plurality of individual continuous light transmissive patterns in the form of the indicia to be displayed. The continuous light transmissive pattern aligned with the display window permits the illuminating means to illuminate selected sets of the light transmissive points on the display window such that the indicia displayed simulates indicia displayed by fiber optic type display devices. The movable mask means is loosely linked to the channel selector shaft and detent means are provided, separately from the tuner detent means, for insuring proper alignment between the mask means and the display window.

United States Patent n91 Gibson et al.

[ SIMULATED FIBER OPTIC VI'IF CI-IANNE INDICIA DISPLAY [75] Inventors: Richard D. Gibson, Wilbraham;

Robert D. Whelan, West Springfield, both of Mass.

[73] Assignee: General Instrument Corporation,

Clifton, NJ.

[22] Filed: Apr. 10, 1974 [21] Appl. No.: 459,661

[52] US. Cl 325/455; 116/124.1 R; 334/86 [51] Int. Cl. H03J 1/02 [58] Field of Search 74/1022; ll6/l24.1 R,

116/1244, 124.1 A, 124 R, 124 A, 124.2 R, DIG. 29, DIG. 31; 325/455, 352; 334/8688; 350/96 B, 96 R; 340/380; 240/21, 1 EL, 2 S;

200/310-312; l78/D1G. 2; 40/130 E Gibson et al 116/124.4

[ Oct. 28, 1975 Primary Examiner-Benedict V. Safourek [5 7] ABSTRACT A VHF channel indicia display device includes a display window made up of a plurality of discrete light transmissive points arranged in a predetermined format on an opaque field. Means are provided for illuminating the display window from the rear. Movable mask means, driven by the channel selector shaft, are interposed between the display window and the illuminating means. The mask means is opaque and has a plurality of individual continuous light transmissive patterns in the form of the indicia to be displayed. The continuous light transmissive pattern aligned with the display window permits the illuminating means to illuminate selected sets of the light transmissive points on the display window such that the indicia displayed simulates indicia displayed by fiber optic type display devices. The movable mask means is loosely linked to the channel selector shaft and detent means are provided, separately from the tuner detent means, for insuring proper alignment between the mask means and the display window.

24 Claims, 5 Drawing Figures US. Patent Oct.28,1975 Sheet 1 of4 3,916,317

US. Patent Oct. 28, 1975 Sheet2 of4 3,916,317

FIG. 2

FIG. 3

US Patent Oct.28, 1975 Sheet3 of4 3,916,317

US. Patent Oct. 28, 1975 Sheet 4 of4 3,916,317

The present invention relates to channel indicia display devices for usewith television tuners or-the like, and more particularly to a channelindicia display for displaying numerals which simulate in appearance those displayed by fiber optic type displays.

It has become mandatory for television receiver manufacturers to include in their tuners UHF tuning mechanisms which are comparable in nature to the VHF tuning mechanisms incorporated in their receivers. In order to achieve this expanded reception, the receiver is normally equipped with separate VHF and UHF tuning elements as well as a separate tuner drive assembly for each of the tuner elements. It is also necessary to provide the receiver with a mechanism for displaying channel indicia corresponding to each of the channels to which the receiver may be tuned. Because of the separation of the tuning functions, two separate channel indicia devices, one for the VHF channels and a second for the UHF channels, must be utilized.

The limited number of channels in the VHF band permits the use of simple channel indicia display devices for displaying numerals corresponding to the VHF channels. Often these display devices consist of a movable disc or drum which has the numerals two through thirteen affixed thereto, each numeral corresponding to one of the available VHF channels. The receiver is provided with a display area, normally slightly larger in size than any one of the numerals, and the disc or drum is operably connected to the VHF channel selector shaft such that as the shaft is rotated the appropriate numeral is brought into alignment with the display area. The display may also be accompanied by a source of illumination to illuminate the displayed numeral which may, in addition, serve as the pilot light for the receiver. This type of display has the advantages of being simple, consisting of low-cost reliable parts, and requiring only a minimum amount of space in the receiver.

With the introduction of receivers having UHF tuning mechanisms comparable to the standard VHF tuning mechanisms, problems have arisen with respect to display devices suitable for use therewith because of the greater number of UHF channels in the UHF band. The seventy UHF channels require a display device which can display seventy numbers having two digits each. Space considerations prohibit the use of the direct viewing method described above for the display of such a large number of numerals. Obviously, in a pracals and utilizing magnification lenses has proven an economically unfeasible alternative.

A different approach, however, hasljb eeit utilized with satisfactory results. This approach has incorpo- 2 rated fiber optics into a channel indicia displayln gen- 6 eral, this type of display utilizes a fiber optic bundle and an illumination source with a mask, ormask's'iriterposed therebetween. The masks are operably connected to the UHF selector shaft to be driven thereby. The movement of the masks permits the illumination of the input ends of the selected fibers which in turn transmit the light to a display'area. The viewer sees a series of discrete illuminated points in the display area which form the numerals corresponding to the channel to which the receiver is tuned. By spreading out the output end of the fibers, an apparent magnification may be achieved. Since the masks may be quite small and manufactured on standard photographic film by a simple process, display devices of this type have been manufactured such that they require only a minimum amount of space in the receiver, are relatively inexpensive to produce and may be reliably operated over long periods of time.

Many television receiver manufacturers plan to utilize the fiber optic method for their UHF channel indicia display device. While it is economically advantageous to utilize a fiber optic display for the UHF band, the aesthetically pleasing fiber optic effect and the FCC requirement of display compatibility require a likewise pleasing display for the VHF tuner. The fewer numbers displayed for VHF channels make the direct view disc approach feasible in this regard if a comparable display could be obtained from such a system.

In a direct view mechanism the mechanical arrangements required to create a display visually comparable with a fiber optic display may cause other problems, namely, that accurate registration of the disc or drum with the display window may become critical to the proper functioning of the display device. This registration is accomplished in conventional direct view displays by utilizing the positioning of the selector shaft which is normally-detented. However, sometimes the detenting of the shaft is not accurate enough for display purposes. In addition, it is not always necessary to have equal intervals of rotation between adjacent channels as the selector shaft is rotated to select different channels. However, with a disc or drum display mechanism, normally the numerals thereon are evenly spaced thus creating an alignment problem if the intervals between selector shaft positions are not precisely equal.

In addition, problems with the alignment of the display mechanisms commonly appear when the tuner associated therewith is replaced. Since the display has no positioning mechanism of its own, certain adjustment procedures must be carried out when the new tuner is connected to the display to provide proper alignment of the disc or drum with the viewing window.

It is, therefore, the prime object of the present invention to provide a VHF channel display which is capable of displaying numerals which simulate the appearance of numerals displayed by fiber optic displays but which utilizes a single disc type mechanism and therefore is compact, reliable and inexpensive to manufacture.

It is a further object of the present invention to provide the dynamic appearance of the UHF fiber optic display-and give no illusion of the rotating numbers while selecting channels.

It is another object of the present invention to provide a VHF channeldisplay having a separate detent mechanism to insure proper alignment thereof regardless of the method used to position the selector shaft.

It is still another object of the present invention to provide a VHF channel display wherein the tuner connected thereto can be replaced without the necessity for the usual display adjustment procedures.

To the accomplishment of the above, and to such other objects as may hereinafter appear, the present invention relates to a simulated fiber optic channel indicia display device as defined in the appended claims and as described in the specification, taken together with the accompanying drawings wherein like numerals refer to like parts and in which:

FIG. 1 is a partially exploded isometric view of a preferred embodiment of the present invention;

FIG. 2 is a front view of the mask means utilized in the preferred embodiment of the present invention;

FIG. 3 is a front view of the display window utilized in the preferred embodiment of the present invention;

FIG. 4 is a side cut-away view of the mechanism shown in FIG. 1; and

FIG. 5 is a cut-away view taken along lines 5-5 of FIG. 4. 1

The preferred embodiment of the present invention is a simulated fiber optic channel indicia display device designed for use in television tuners or the like in conjunction with the tuner drive assembly utilized to corporeally condition the tuning element to select the desired channel. Tuner drive assemblies and VHF tuning elements are well known in the art and the particular form of each of these mechanisms utilized in the television receiver forms no portion of the present invention. For this reason the tuning element utilized herein is depicted as being situated within a metallic enclosure, generally designated A, as is common in the art. The tuner drive assembly, generally designated B, is manipulated to corporeally condition the tuning element by means of the rotation of a tuning shaft, generally designated C, one end of which extends to the exterior of the receiver enclosure to provide accessibility such that it may be manipulated to achieve fine tuning and channel selection.

A support comprising an opaque front panel, which may be a portion of the receiver enclosure or a separate sheet of material affixed thereto, is provided. Within the front panel is situated a display window, generally designated D, which may be a plastic or glass insert in the front panel. Display window D is provided with a plurality of discrete light transmissive points, generally designated E, which are arranged in a predetermined format on an opaque field. Means, generally designated F, are preferably situated behind the panel, are provided to illuminate the display window D.

Movable mask means, generally designated G, are interposed between display window D and illuminating means F. Mask means G is operably connected to tuning shaft C such that the rotation of tuning shaft C will move mask means G. Mask means G has a plurality of individual continuous light transmissive patterns, generally designated H, arranged in a circular configuration on the surface thereof. Each of these individual continuous light transmissive patterns H forms a numeral corresponding to one of the VHF channels. Upon alignment of a particular pattern H with display window D, light from illuminating means F passes through the aligned pattern and illuminates selected points E on display window D. The illuminated points form a pattern recognizable as a numeral and the display appears similar to that which would be formed by a fiber optic display.

Referring now to FIGS. 1 and 4, the VHF tuning element incorporated within enclosure A is corporeally conditioned by means of tuner drive assmebly B. As-

sembly B in turn is manipulated by control shaft C which actually comprises a pair of coaxial shafts, coarse tuning shaft 10 and fine tuning shaft 12. The shafts extend to the exteriorsurface of front panel 13 wherein they areconnected to a pair of independer" rotatable coaxial control knobs 14 and 16. The rotat. of knob 14 drives coarse .tuning shaft 10. In a similar manner, the rotation of knob 16 rotates fine tuniz. shaft 12.

Coarse tuning shaft 10 drives disc 18 which is the channel selection input of the tuning element. Disc 18 is detented in the conventional manner by a detent mechanism comprising a spring 19 urging a ball 22 into contact with the recesses along the edge of disc 18. Shaft C has a knurled portion 23 to which a collar 24 is fixedly mounted. Collar 24 extends forward (right as seen in the drawing) and is loosely connected to linking member 25 which in turn supports mask G. Member 25 and collar 24 are loosely linked to provide for the separate detenting of mask G.

Collar 24 is provided with several notches or recesses 20 along the edge thereof. The preferred embodiment has three such notches, only two of which are visible in FIGS. 1 and 4. Member 25 is provided with a plurality of protrusions 20a each of which is aligned with a different one of the notches 25. Protrusions 20a fit loosely into the corresponding notches 20 to provide the mechanical connection between collar 24 and member 25. Protrusions 20a are somewhat smaller in size than notches 20 such that the connection between collar 24 and member 25 is provided with a substantial amount of play. This play permits the use of the independent display detent means.

Member 25 carries a detent wheel 27 which communicates with a roller 29 urged by a spring 31 against the recesses along the edge of wheel 27. Spring 31 is mounted on support 33 by any suitable means such as screw 35. The loose connection between member 25 and collar 24 permits the independent detenting of mask G. Thus, the lack of accuracy of the detent mechanism associated with the selector shaft does not adversely effect the display mechanism and excellent registration between mask G and display window D is always achieved. Further, the rotational intervals between channel selection positions need not be precisely equal in order to provide for the proper registration between mask G and window D.

Rotatably mounted on collar 24 is a drive shaft 26 carrying a pair of gears 28 and 30, one of which is located on each end thereof. Shaft 26 is radially offset from shaft 10 and therefore revolves about the axis of rotation of shaft 10 as shaft 10 is rotated. Shaft 26 and gears 28 and 30 serve as a mechanical link between fine tuning shaft 12 and the remainder of the fine tuning portion of assembly B.

Fine tuning shaft 12 is provided with a gear 32 which meshes with gear 28 such that the rotation of shaft 12 rotates shaft 26. Gear 30, on the rear of shaft 26, meshes with gear 34 rotatably mounted on shaft 10. Gear 34 in turn rotates a clutch 36. Clutch 36 engages a plate 37 which is mounted on enclosure A for movement parallel to the front wall thereof (as indicated by arrow 43 Clutch 36 has a disc shape with a pair of diametrically opposed protrusions 39 extending radially therefrom. The rotation of clutch 36 causes one of the protrusions 39 (which one depends upon the direction of rotation) to engage the appropriate one of the recesses 41'on-plate 37 and'move platel37 in. the direction of arrow 43:; Further rotation of gearJSW-rotat'es gear 40. When plate 37 is moved by clutch 36;"gear40 Q in different arrangements may also be, utilized as-demeshes with a gear 42 rotatably mounted on plate 37. I

Gear 42*rotates-shaft"47 also rotatably mounted on plate 37. A gear 44, mount'ed'on the rear of shaft 47, meshes with a gear 45 which is the fine tuning inp ut of the tuner. When-knob :16 is released, a spring 48, mounted to thefront'wall of enclosure A ,mov"esjplate 37 back to itsoriginal position (as showninIFIG. 1), thus disconnecting gear 40 from-gear 42. This disconnects thefine' tuning knob 16 from the tuner and permits channel changes while perserving the ,finetuning setting. a I r V I The initial'rotation of knob 15 rotates shaft 26 and thus clutch 36 to move plate-37 and operatively connect gear 40 to input gear'45. Further rotation of knob 16 causes the rotation of gear 45 to accomplish fine tuning. Channel selection is accomplished by rotating knob 14 and thus shaft which rotates collar 24. The rotation of shaft "10 causes gear 18 to revolve thus se lecting the desired channel. The rotation of collar 24 rotates mask G to' bring the appropriate portion thereon into alignment with 'display window=D.

In thismanner, the rotation of knob 14 rotates mask nel. This rotation also causes the-rotation of collar 24 and of disc-60. Disc 60 is independently detented into position to assure accurate alignment with window D.

meansG and input gear 18 thus synchronizing the dis- I fine tuning setting.

Fine tuning knob 16 may be rotated to rotate' fine tuning shaft 12 and thus drive the tuner drive assembly to corporeally condition the tuning element to provide fine tuningfbut this has no effect on the position of disc 60. The light transmissive pattern H which is aligned with display window D corresponds to the channel selected. The light from. illuminating means F passes through the light transmissive pattern H in the operable position and illuminates selected light transmissive points E .on display window D. The visual effect at display window D is a series of points of light in a pattern which forms the desired numeral.

In FIG. 1 the light transmissive pattern H corresponding to channel 12 is'in the operative position between illuminating means F and display window D. Therefore, each of the points E in pattern 68 is illuminated to create a one forthe tens digit and selected points E in pattern 70 are illuminated to produce the two. for the units digit thus forming the numeral 12. When channel selector knob 14 isagain rotated,'a differentlight transmissive pattern H is aligned withdisplayiwindow D. and

Movable mask G is preferably in the form of a disc 60 mounted on a transparent support disc 6130 provide the necessary structuralsupporti; Disc 60 has an opaque field 62 and a plurality of individual continuous light transmissive patterns I-I in the form of indicia. This can most clearly be seen in' FIG. 2. As shown in this figure,

thus differentlight transmissive points E will be :illuminated to produce a different numeral; q

The present invention producesa channel indicia. display which simulates that which would be-produced by v a fiber optic display. This is true not only when the channel'is set but also between channels wherein the flashing dots appearance of a fiber optics display in the individual continuous light transmissive'patterns l-I form a'plurality o f'numerals' two through 13 which are situated ina circular formation along the surface of disc 60. Betw'een'numerals two and 13 is situateda conshaft 10 must be rotated forUl-IF reception in a manner common in many television receivers having both VHF and UHF receiving capability. V

Illuminating means'F is'situate'd behind disc 60 and comprises a bulb 64 and a reflector 67 capable of directing a beam of light towards the rear surface of disc 60. Preferably, bulb 64 is energized when the television receiver is turned on and therefore may serve the additional purpose of being a pilot light.

As best shown in FIG. 3, display window D situated on front panel 13 comprises a plurality of discrete light transmissive points E on an opaque field 66. Preferably, points E are divided into a straight line 68 and a pattern 70 comprised of three rows intersected by three columns. Straight line 68 is comprised of eight points while pattern 70 is comprised of 30 points, making a total of 38 points. Pattern 68 represents the tens digit of the numeral to be displayed. For VHF channels this digit may only be blank or one. Pattern 70 corresponds to the units digit which may be any of the digits zero through nine. It has been found that this configuration of 38 light transmissive points arranged in the illustrated manner is capable of producing an aesthetically pleasing display. However, different numbers of points transition is also simulated. In addition, the mechanical arrangement of the present invention permits the replacement of thetuner without the usual display adjustments primarily due to the independent detenting of the display. Further, these features are accomplished in a relatively inexpensive manner by means of simple, reliable and sturdy parts which take up a minimum amount of room in the tuner. Thus, the present invention achieves a VHF channel indicia display which has all the advantages of the conventional direct view display device and the-additional advantage that it is.visually compatiblewith UHF display devices of thefiber optic type. I s

A preferred embodiment of the present invention has been specifically disclosed herein for purposes of illustration. It is apparent that many modifications and variations may be made upon the specific structure disclosed herein. It is intended to cover all of these variations and modifications which fall within the scope of this invention as defined by the appended claims.

We claim:

1. A simulated fiber optic display for use with a television tuner or the like of the type having a channel selecting tuning member, said display comprising a support, an opaque stationary mask mounted on said support and having a plurality of light transmissive points arranged in a predetermined format, means for illuminating said stationary mask, and a movable mask interposed between said stationary mask and said illuminating means, said movable mask being operably connected to said tuning member to be driven thereby and having a plurality of individual continuous indiciashaped transparent patterns such that when one of said patterns aligns with said mask, selected sets of said points are illuminated, thereby causing the visual effect of a fiber optic display.

2. The display of claim 1 wherein there are 38 of said points.

3. The display of claim 2 wherein said format is divided into a tens section and a units section.

4. The display of claim 1 wherein said format is divided into a tens section and a units section.

5. The display of claim 4 wherein said tens section comprises a plurality of points arranged in a straight line.

6. The display of claim 5 wherein said units section comprises thirty points arranged in three rows intersecting three columns.

7. The display of claim 1 wherein said movable mask is mounted on a movable support, and further comprising detent means acting directly on said mask support to position said mask means.

8. The display of claim 7 wherein said mask support is loosely linked to said channel selecting tuning member.

9. A simulated fiber optic display for displaying indicia corresponding to the VHF channels in a television receiver or the like having both VHF and UHF tuning capability and VHF and UHF control shafts for control thereof and wherein the indicia corresponding to the UHF channels are displayed with a fiber optic display device, said simulated display comprising a support, an opaque stationary mask mounted on said support and having a plurality of light transmissive points arranged in a predetermined format, means for illuminating said stationary mask, and a movable mask interposed between said stationary mask and said illuminating means, said movable mask being operably connected to said VHF control shaft to be driven thereby and having a plurality of individual continuous indicia-shaped transparent patterns such that when one of said patterns aligns with said mask, selected sets of said points are illuminated, thereby causing a visual effect which is similar to the effect created by said fiber optic display device.

10. The display of claim 9 wherein there are 38 of said points.

1 1. The display of claim 10 wherein said format is divided into a tens section and a units section.

12. The display of claim 9 wherein said format is divided into a tens section and a units section.

13. The display of claim 9 wherein said tens section comprises a plurality of points arranged in a straight line.

14. The display of claim 13 wherein said units section comprises 30 points arranged in three rows intersecting three columns.

15. The display of claim 9 wherein said movable mask is mounted on a movable support, and further comprising detent means acting directly on said mask support to position said mask means.

16. The display of claim 15 wherein said mask support is loosely linked to said channel selecting tuning member.

17. A channel indicia display for use with a television tuner or the like of the type having a detented channel selecting member, said display comprising a support, an opaque stationary mask mounted on said support having a display window therein, means for illuminating said stationary mask and a movable mask interposed between said stationary mask and said illuminating means, said movable mask being operably connected to said member to be driven thereby, said connection permitting limited relative movement between said member and said movable mask and detent means, independent of the detent mechanism acting on said member, for detenting said movable mask thereby providing accurate registration between said movable mask and said window.

18. The display of claim 17 wherein said window comprises a plurality of light transmissive points arranged in a predetermined format.

19. The display of claim 18 wherein said movable mask has a plurality of individual continuous indiciashaped transparent patterns thereon.

20. The display of claim 19 wherein there are 38 of said points.

21. The display of claim 19 wherein said format is divided into a tens section and a units section.

22. The display of claim 20 wherein said format is divided into a tens section and a units section.

23. The display of claim 22 wherein said tens section comprises a plurality of points arranged in a straight line.

24. The display of claim 23 wherein said units section comprises 30 points arranged in three rows intersecting three columns. 

1. A simulated fiber optic display for use with a television tuner or the like of the type having a channel selecting tuning member, said display comprising a support, an opaque stationary mask mounted on said support and having a plurality of light transmissive points arranged in a predetermined format, means for illuminating said stationary mask, and a movable mask interposed between said stationary mask and said illuminating means, said movable mask being operably connected to said tuning member to be driven thereby and having a plurality of individual continuous indicia-shaped transparent patterns such that when one of said patterns aligns with said mask, selected sets of said points are illuminated, thereby causing the visual effect of a fiber optic display.
 2. The display of claim 1 wherein there are 38 of said points.
 3. The display of claim 2 wherein said format is divided into a tens section and a units section.
 4. The display of claim 1 wherein said format is divided into a tens section and a units section.
 5. The display of claim 4 wherein said tens section comprises a plurality of points arranged in a straight line.
 6. The display of claim 5 wherein said units section comprises thirty points arranged in three rows intersecting three columns.
 7. The display of claim 1 wherein said movable mask is mounted on a movable support, and further comprising detent means acting directly on said mask support to position said mask means.
 8. The display of claim 7 wherein said mask support is loosely linked to said channel selecting tuning member.
 9. A simulated fiber optic display for displaying indicia corresponding to the VHF channels in a television receiver or the like having both VHF and UHF tuning capability and VHF and UHF control shafts for control thereof and wherein the inDicia corresponding to the UHF channels are displayed with a fiber optic display device, said simulated display comprising a support, an opaque stationary mask mounted on said support and having a plurality of light transmissive points arranged in a predetermined format, means for illuminating said stationary mask, and a movable mask interposed between said stationary mask and said illuminating means, said movable mask being operably connected to said VHF control shaft to be driven thereby and having a plurality of individual continuous indicia-shaped transparent patterns such that when one of said patterns aligns with said mask, selected sets of said points are illuminated, thereby causing a visual effect which is similar to the effect created by said fiber optic display device.
 10. The display of claim 9 wherein there are 38 of said points.
 11. The display of claim 10 wherein said format is divided into a tens section and a units section.
 12. The display of claim 9 wherein said format is divided into a tens section and a units section.
 13. The display of claim 9 wherein said tens section comprises a plurality of points arranged in a straight line.
 14. The display of claim 13 wherein said units section comprises 30 points arranged in three rows intersecting three columns.
 15. The display of claim 9 wherein said movable mask is mounted on a movable support, and further comprising detent means acting directly on said mask support to position said mask means.
 16. The display of claim 15 wherein said mask support is loosely linked to said channel selecting tuning member.
 17. A channel indicia display for use with a television tuner or the like of the type having a detented channel selecting member, said display comprising a support, an opaque stationary mask mounted on said support having a display window therein, means for illuminating said stationary mask and a movable mask interposed between said stationary mask and said illuminating means, said movable mask being operably connected to said member to be driven thereby, said connection permitting limited relative movement between said member and said movable mask and detent means, independent of the detent mechanism acting on said member, for detenting said movable mask thereby providing accurate registration between said movable mask and said window.
 18. The display of claim 17 wherein said window comprises a plurality of light transmissive points arranged in a predetermined format.
 19. The display of claim 18 wherein said movable mask has a plurality of individual continuous indicia-shaped transparent patterns thereon.
 20. The display of claim 19 wherein there are 38 of said points.
 21. The display of claim 19 wherein said format is divided into a tens section and a units section.
 22. The display of claim 20 wherein said format is divided into a tens section and a units section.
 23. The display of claim 22 wherein said tens section comprises a plurality of points arranged in a straight line.
 24. The display of claim 23 wherein said units section comprises 30 points arranged in three rows intersecting three columns. 